1/*
2 * Copyright (c) 2012 Linaro : Daniel Lezcano <daniel.lezcano@linaro.org> (IBM)
3 *
4 * Based on the work of Rickard Andersson <rickard.andersson@stericsson.com>
5 * and Jonas Aaberg <jonas.aberg@stericsson.com>.
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/module.h>
13#include <linux/cpuidle.h>
14#include <linux/spinlock.h>
15#include <linux/atomic.h>
16#include <linux/smp.h>
17#include <linux/mfd/dbx500-prcmu.h>
18#include <linux/platform_data/arm-ux500-pm.h>
19#include <linux/platform_device.h>
20
21#include <asm/cpuidle.h>
22
23static atomic_t master = ATOMIC_INIT(0);
24static DEFINE_SPINLOCK(master_lock);
25
26static inline int ux500_enter_idle(struct cpuidle_device *dev,
27				   struct cpuidle_driver *drv, int index)
28{
29	int this_cpu = smp_processor_id();
30	bool recouple = false;
31
32	if (atomic_inc_return(&master) == num_online_cpus()) {
33
34		/* With this lock, we prevent the other cpu to exit and enter
35		 * this function again and become the master */
36		if (!spin_trylock(&master_lock))
37			goto wfi;
38
39		/* decouple the gic from the A9 cores */
40		if (prcmu_gic_decouple()) {
41			spin_unlock(&master_lock);
42			goto out;
43		}
44
45		/* If an error occur, we will have to recouple the gic
46		 * manually */
47		recouple = true;
48
49		/* At this state, as the gic is decoupled, if the other
50		 * cpu is in WFI, we have the guarantee it won't be wake
51		 * up, so we can safely go to retention */
52		if (!prcmu_is_cpu_in_wfi(this_cpu ? 0 : 1))
53			goto out;
54
55		/* The prcmu will be in charge of watching the interrupts
56		 * and wake up the cpus */
57		if (prcmu_copy_gic_settings())
58			goto out;
59
60		/* Check in the meantime an interrupt did
61		 * not occur on the gic ... */
62		if (prcmu_gic_pending_irq())
63			goto out;
64
65		/* ... and the prcmu */
66		if (prcmu_pending_irq())
67			goto out;
68
69		/* Go to the retention state, the prcmu will wait for the
70		 * cpu to go WFI and this is what happens after exiting this
71		 * 'master' critical section */
72		if (prcmu_set_power_state(PRCMU_AP_IDLE, true, true))
73			goto out;
74
75		/* When we switch to retention, the prcmu is in charge
76		 * of recoupling the gic automatically */
77		recouple = false;
78
79		spin_unlock(&master_lock);
80	}
81wfi:
82	cpu_do_idle();
83out:
84	atomic_dec(&master);
85
86	if (recouple) {
87		prcmu_gic_recouple();
88		spin_unlock(&master_lock);
89	}
90
91	return index;
92}
93
94static struct cpuidle_driver ux500_idle_driver = {
95	.name = "ux500_idle",
96	.owner = THIS_MODULE,
97	.states = {
98		ARM_CPUIDLE_WFI_STATE,
99		{
100			.enter		  = ux500_enter_idle,
101			.exit_latency	  = 70,
102			.target_residency = 260,
103			.flags		  = CPUIDLE_FLAG_TIMER_STOP,
104			.name		  = "ApIdle",
105			.desc		  = "ARM Retention",
106		},
107	},
108	.safe_state_index = 0,
109	.state_count = 2,
110};
111
112static int dbx500_cpuidle_probe(struct platform_device *pdev)
113{
114	/* Configure wake up reasons */
115	prcmu_enable_wakeups(PRCMU_WAKEUP(ARM) | PRCMU_WAKEUP(RTC) |
116			     PRCMU_WAKEUP(ABB));
117
118	return cpuidle_register(&ux500_idle_driver, NULL);
119}
120
121static struct platform_driver dbx500_cpuidle_plat_driver = {
122	.driver = {
123		.name = "cpuidle-dbx500",
124	},
125	.probe = dbx500_cpuidle_probe,
126};
127
128module_platform_driver(dbx500_cpuidle_plat_driver);
129